Showing papers on "Halide published in 1986"

Thermal transfer sheet

Abstract: PURPOSE:To provide a heat-meltable ink layer enhanced in transfer efficiency, close adhesiveness and transparency and having no problem of bleeding, by providing two layers, that is, a resistance layer and an ink layer containing halide and/or a phosphorus compound CONSTITUTION:The titled transfer sheet has two layers, that is, a resistance layer and an ink layer containing halide and/or phosphorus compound and, pref, 5-40ptswt of halide with mp of 70-110 degC and/or 10-30ptswt of the phosphorus compound are contained in the ink layer If mp of halide is below 70 degC, said halide causes bleeding (exudation) on the surface of the ink layer and, if 110 degC or more, the lowering in the transfer efficiency of ink results When halide is below 5ptswt, the sharp enhancement in transfer efficiency is achieved and, when 40ptswt or more, the lowering of transfer efficiency and the lowering in transparency and close adhesiveness result When the phosphorus compound is below 10ptswt, the close adhesiveness to a base material is inferior and, when 30ptswt or more, the plasticizing property possessed by the phosphorus compound is unnecessarily too strong and a bleeding phenomenon is generated

Acid catalysis by dealuminated zeolite Y. 2. The roles of aluminum

Abstract: Hexane cracking activity was determined for a series of dealuminated zeolites which were prepared both by treatment with SiCl/sub 4/ and by reaction with steam. Over a range of Si/Al ratios from 4.7 to 255 the cracking activity increased in a linear manner with respect to the number of lattice Al ions per unit cell. Thus, a constant turnover frequency is obtained, which is taken as evidence that the acid strength does not vary over this range of Si/Al ratios. By contrast, a zeolite prepared by deamination of NH/sub 4/-Y was very much less active than expected on the basis of the number of protonic sites. The acidity of the protons in this material is clearly less than in the dealuminated zeolite. These results support a model of strong Broensted acidity in which a structural aluminum atom has no next-nearest aluminum neighbors in a common 4-ring of the zeolite.

Room-temperature ionic liquids as solvents for electronic absorption spectroscopy of halide complexes

Abstract: Solution studies of halide complexes of the transition metals, of general type [MXn]y− (X=Cl or Br), have been severely hampered by the existence of both solvation and solvolysis phenomena1. We demonstrate here that the use of room-temperature ionic liquids (often misleadingly referred to as molten salts) as solvents circumvents both of these problems, and permits the first reliable solution spectra to be recorded for these species; in some cases the spectra exhibit quite remarkable resolution.

Viscoelastic collagen solution for ophthalmic use and method of preparation

Abstract: Chemically-modified collagen is prepared by reacting native collagen with a di or tri-carboxylic acid halide, di or tri-sulfonyl halide, di or tri-anhydride, or di or tri-reactive active ester coupling agent. The reaction is done in a controlled manner so that the degree of cross-linking is limited. Any remaining lysine epsilon amino groups present in the coupled collagen product may be converted to carboxyamido or sulfonamido groups by acid halide, anhydride, sulfonyl halide or active ester amine-modifying agents. The resultant product when dissolved in a physiological buffer provides a viscoelastic solution having therapeutic application in a variety of surgical procedures, particularly in ophthalmic surgery. This viscoelastic solution "melts," i.e., exhibits a dramatic loss of viscosity, when subjected to temperatures of between 32° and 48° C.

Layered double hydroxides as supported anionic reagents. Halide-ion reactivity in zinc chromium hexahydroxide halide hydrates [Zn2Cr(OH)6X.nH2O] (X = Cl, I).

Abstract: Several new families of heterogeneous catalysts recently have been synthesized by intercalating metal ions and cationic metal complexes between the negatively charged layers of smectite clay A complementary class of layered compounds exist in which the charge on the layers and gallery ions is the reverse of that found for smectite clays. These are the layered double hydroxides (LDH's) of the type [M,\"M,\"'(OH)2(++V)]A,,,. Z H ~ O . ~ ~ The positively charged layers are brucitelike (MI(OH)~) with trivalent cations substituting for divalent cations in octahedral sites of the hydroxide sheet. Typically, the ratio y / x is in the range 0.20-0.50. In naturally occurring LDH minerals the interlayer anion A\"is most commonly carbonate as in hydrotalcite, Mg6A12(OH) 16(C03).4H20, and pyroaurite, M&Fe2(0H)16(C03). 4H20. However, a wide range of derivatives containing various combinations of MI', MI1', and A\" ions can be synthesized either by direct crystallization@ from aqueous solution or by anion exchangelo for A\" in a precrystallized host. LDH's have been investigated as solid ionic conductors\" and as catalyst p rec~rsors , '~J~ but the properties of the pristine compounds as supported anionic reagents or as catalysts for chemical synthesis have not been addressed. Unlike the galleries of smectites, which can be swelled by multiple layers of solvent to mimic a solution-like environment,' the galleries of LDH's accommodate only one or two layers of water and other polar molecules. This limitation in gallery swelling, along with the relatively high layer charge density, means that typical organic reagents are unable to penetrate the intracrystal space occupied by the anions. Here we demonstrate that although the gallery anions in a typical LDH are not accessible for direct intracrystalline reaction, they are readily transferred to external edge surfaces for reaction with substrates adsorbed at those sites. The reactions investigated were simple halide-exchange processes between the halide ions in Zn2Cr(OH)6X.H20 and alkyl halides in the condensed state (toluene) or in the vapor phase. The chloride form of the LDH was prepared by reaction of aqueous CrC13 with ZnO according to previously described p r o c e d ~ r e s . ~ ~ J ~

Electron affinities of the alkali halides and the structure of their negative ions

Abstract: Photoelectron spectra are reported for the MX (X 1Σ+)+e−←MX−(X 2Σ+) transitions of ten alkali halide anions at 488 nm. Adiabatic electron affinities (±0.010 eV) are determined to be 0.593 (LiCl), 0.520 (NaF), 0.727 (NaCl), 0.788 (NaBr), 0.865 (NaI), 0.582 (KCl), 0.642 (KBr), 0.728 (KI), 0.543 (RbCl), and 0.455 eV (CsCl). Fundamental vibrational frequencies, equilibrium bond lengths, and dissociation energies are also reported for the anion 2Σ+ ground states. An observed linear correlation of electron affinities with α/r2 (α=metal atom polarizability) is used to predict the electron affinities of the remaining alkali bromides and iodides, as well as related alkali salts. A simple electrostatic model for the alkali halide anions is also presented which enables the accurate (±0.1 eV) calculation of electron affinities.

Catalyst system for use in olefinic polymerization

Abstract: A catalyst system for use in olefinic polymerization and copolymerization is comprised of components (A), (B) and (C). The catalyst component (A) consisting essentially of titanium, magnesium, halogen, polycarboxylic acid esters and organic phosphorus compounds is a solid product, being prepared by mixing titanium tetrahalide and auxiliary precipitant with a homogeneous solution of magnesium halide in a solvent system consisting essentially of an organic epoxy compound and an organic phosphorus compound to form a solid product which is then treated with a polycarboxylic acid ester and titanium tetrahalide. Component (B) is an organic aluminum compound, and component (C) is an organic silicon compound. The catalyst system has a very high activity, and the resultant polymers have very high stereospecificity and good granular appearance.

Method of refining rare gas fluoride excimer laser gas

Abstract: METHOD OF REFINING RARE GAS HALIDE EXCIMER LASER GAS A laser gas used in a rare gas halide excimer laser is efficiently refined with little loss of the essential rare gas such as Kr, Ar or Xe by contact of the laser gas with a solid alkaline compound, e.g. Ca(OH)2, for conversion of acidic impurities and also the halogen source gas such as F2 or HCl into solid metal halides and contact of the remaining gas with zeolite which is adsorbent of the remaining impurities. When the halogen source gas comprises a highly oxidizing fluorine matter the laser gas is first brought into contact with a reactive metal, e.g. Si or Fe, to convert the oxidizing fluorine matter into metal fluorides to thereby prevent formation of O2, which is obstructive to the laser operation, by reaction of the oxidizing matter with the alkaline compound. The halogen source gas too can be recovered by initially cooling the laser gas so as to cause condensation of the rare gas and impurities having relatively high boiling points and leave the halogen source gas, which is lower in boiling point, in gas phase.

Impedance studies of corrosion resistance of aluminium in chloride media

Abstract: The electrochemical behaviour of aluminium in chloride solutions has been studied. Open-circuit impedance measurements reveal that in both acidic and neutral media the dissolution of the oxide formed on aluminium is governed by an empirical relation of the form C m -1 = a − Bt 1 2 where a and B are constants. The rate of the oxide film dissolution in the chloride-containing solutions is found to be markedly lower than that in other halide media, especially in fluoride solutions. The behaviour of the oxide is determined by the pH of the dissolution medium rather than its chloride ion content. Complex plane analysis of the anodic oxide film formed on aluminium indicates that the corrosion resistance is very high in neutral chloride solutions in comparison with acid solutions containing the same amount of chloride ions. Both the charge transfer resistance θ and the Warburg impedance caused by diffusional mass transfer attain markedly higher values in the neutral media which reflect the high passivation properties of the oxide film. It is suggested that many constructions could be coated with aluminium oxide films to protect them from corrosion, especially in marine media.

Effect of Growth Conditions on Halomethane Production by Phellinus Species: Biological and Environmental Implications

Abstract: Production of the gaseous secondary metabolite chloromethane (CH,Cl) by the fungus Phellinus pomaceus has been measured on a variety of media using headspace techniques. On glucosebased media, CH3C1 production was linearly related to the logarithm of chloride ion concentration. At concentrations less than 4 mM, over 90% of the chloride ion in the medium was converted to CH3C1. Bromide and iodide, but not fluoride, were substrates for the methylating system. The pH range 5 to 7 was optimal for CH3C1 biosynthesis and the presence of ammonium ions stimulated the process. Supplementation of the medium with methionine, serine or folic acid did not affect overall CH3CI production. With cellulosic media, CH3C1 yields based on chloride ion present in the medium were high, ranging from 75% at 0.4 mM to 90% at 50m~. Bromomethane yields from bromide averaged 70% between 0.5 and 25 mM. Iodomethane yields of approximately 60% were obtained with up to 1 mM-iodide but declined sharply above this concentration. When equimolar concentrations of the three halide ions were present, the different halides were methylated sequentially, iodide being the most preferred substrate and chloride the least. Gas chromatography/mass spectrometry of other headspace volatiles from P. pomaceus mycelia revealed, amongst the main components, methyl esters of 2-furoic, benzoic and salicylic acids. The pseudohalide ion thiocyanate acted as a specific inhibitor of not only halomethane biosynthesis but also methyl benzoate formation, suggesting that methylation of halide and benzoate may be mediated by the same biochemical system. Of five other species of Phellinus previously reported to produce CH,Cl, only P. ribis and P. occidentalis exhibited high efficiency conversion of chloride ion to CH3Cl. P. robiniae converted only a small proportion of available chloride to CH3Cl, whilst no CH3Cl production by P. conchatus or P. vinosus could be demonstrated on any of the media employed. The biochemical, ecological and environmental significance of fungal halomethane biosynthesis is discussed.

The nucleation of lead from halide-containing solutions

Abstract: The density of active sites and the nucleation rates per site for the nucleation of lead onto vitreous carbon from lead ion solutions in the presence of halides (Cl−, Br−, I−) have been investigated. Mass transport to growing nuclei was not found to be affected by the formation of soluble complexes of lead with the halides. No systematic variation of the true nucleation rates per site was observed upon addition of halides to the electrolyte. The density of active sites for nucleation, on the other hand, increased in the presence of halides. It is also shown that, in the absence of halide ions, the density of active sites for the nucleation of both lead and silver are equal to and independent of the concentration of metal ions in solution.

Halide formation and etching of Cu thin films with Cl2 and Br2

Abstract: Etching mechanisms of Cu thin films under the exposure of an argon ion beam and halogen molecules (Cl2, Br2) were examined in a UHV system using a quartz crystal oscillator and x‐ray photoelectron spectrometer. Chlorine exposure at room temperature produced a very stable chlorine overlayer on the Cu surface. The passivation of Cu by chemisorbed Cl reduced the etch rate of Cu film under argon ion bombardment for pressure up to 10−3 Torr of chlorine. Cuprous chloride was formed at 210 K, where multilayers of Cl2 are adsorbed on the Cu surface. Br2, however, diffused into the Cu substrate at 10−6 Torr at room temperature. A linear growth rate of the halide film was observed. The etch rates of copper were not enhanced by ion bombardment in the presence of either halogen. Large amounts of free halogens were incorporated in the halide films. These results suggest that the halogenation of a copper surface is dominated by the unactivated place exchange mechanism with constant sticking coefficient. The relative fl...

Method for synthesizing mgo-a12o3- sio2 glasses and ceramics

Abstract: A vapor phase method for the synthesis of Mg0-A1203-Si02 products, including Mg0-Al203-Si02 glasses of optical quality, wherein SiCl4, aluminium halide, and organometallic magnesium vapors are oxidized by flame oxidation and the oxides collected and sintered to glass or ceramic products, is described. A added shield gas stream is provided during flame oxidation of the vapors to reduce or prevent MgC12 by-product formation at the burner and in the product.

Hydrogen iodide in argon matrices

Abstract: The infrared spectra and HI and DI in argon matrices have been studied in the 11-25 K interval. The effects of concentration changes and of impurities have been investigated. Dimer and trimer bands have been assigned, as well as bands due to binary complexes with water, hydrogen bromide, hydrogen chloride, and atomic and molecular iodine.

F -center production in alkali halide crystals by monochromatic x-ray and ultraviolet radiation.

Abstract: The spectral dependence of the F-center production efficiency was observed in the hard-x-ray region at the K edge of bromine in KBr and in the near-ultraviolet part of the spectrum corresponding to the exciton region of several alkali halides. Evidence of a definite increase at the core threshold was observed as well as a significant wavelength dependence of the F-center production efficiency in the near-uv region. These studies were made possible by the development of an extremely sensitive method of detecting F centers in ultralow concentrations, which utilizes the luminescent properties of these centers.